NBC News reports that French investigators have recovered the airplane's cockpit voice recorder. Though damaged, it is still possible that it could provide insight into the cause of the crash. While a range of possible explanations are still being considered, French Interior Minister Bernard Cazeneuve said that a terrorist attack was not likely.

The crash site investigation and recovery operation resumed Wednesday morning, according to Euronews. Due to the mountainous nature of the terrain surrounding the crash site, as well as bad weather, the recovery effort is likely to take some time.

“We are entering a phase of criminal investigation which will be long,” French Interior Ministry spokesperson Pierre Henry Brandet told Euronews. “It has to be done in a very precise way, with meticulous detail in order to find the bodies, to allow for their identification, and to give them back to their families, while of course collecting the evidence which will help advance the investigation.”

What Caused the Crash?

While it is much to early to know for sure the cause of the crash, aviation experts are beginning to discuss potential options. Scott Mayerowitz of the Associated Press has raised three potential causes:

1. Rapid Decompression

Each takeoff and landing cycle of an airplane involves pressurization and depressurization of the cabin, which puts stress on the metal skin of the aircraft. Short flight of the kind made by the Germanwings aircraft are more vulnerable to this phenomenon because they go through more pressurization / depressurization cycles. If the airplane did depressurize rapidly, it could have prompted the plane's rapid descent.

2. Technical Error

Failures in instrumentation or autopilot have also been known to cause accidents in the past.

3. Pilot Error

Pilot error, such as accidentally putting the plane into a dive or stall and being unable to recover, could also have contributed to the accident.